The present invention relates to a method for setting armature lift in a fuel injector.
In previous armature/needle lift setting operations for a fuel injector, the desired amount of lift of the body/armature/needle subgroup relative to the inlet tube/shell subgroup is set through a step-by-step press operation. The maintenance of the final position of between the two subgroups is obtained through an interference fit between the two subgroups and a final welding process. It is believed that, with this process, the assembling of the subgroups to obtain a desired lift distance requires utmost care and, if the lift distance is established incorrectly, the subgroups cannot be cost effectively disconnected from each other.
It would be beneficial to develop an injector in which the lift setting can be measured and adjusted after assembly and a method of setting the injector lift in which the lift can be adjusted during assembly of the injector.
Briefly, the present invention is an armature lift assembly comprising a body having an upstream end, a downstream end, and a longitudinal body channel extending therethrough and an armature/needle assembly reciprocably disposed in the body along the longitudinal body channel. The armature lift assembly also includes a first tube having an upstream end, a downstream end fixedly connected to the upstream end of the body, and a first tube channel. The assembly also includes a second tube located within the first tube channel and fixedly connected to the first tube. The second tube has an upstream end and a downstream end. The downstream end of the second tube is spaced a distance from the upstream end of the armature/needle assembly approximately equal to a lift distance of the armature/needle assembly.
The present invention also provides a fuel injector comprising an armature lift assembly including a body having an upstream end, a downstream end, and a longitudinal body channel extending therethrough and an armature/needle assembly reciprocably mounted in the body along the longitudinal body channel. The armature lift assembly also includes a first tube having an upstream end, a downstream end fixedly connected to the upstream end of the body, and a first tube channel and a second tube located within the first tube channel and fixedly connected to the first tube. The second tube has an upstream end and a downstream end. The downstream end of the second tube is spaced approximately equal to the armature/needle assembly lift distance from the upstream end of the armature/needle assembly. The fuel injector also includes a seat proximate to the armature/lift assembly so that the armature/needle assembly engages the seat in a closed position.
The present invention also provides a method of setting armature lift in a fuel injector having a first tube fixedly connected to a body, the body containing an armature reciprocably disposed therein, the method comprising: inserting a second tube into the first tube, a downstream end of the second tube engaging the armature; inserting a lift gage through the second tube; and separating the second tube from the armature, the lift gage biasing the armature away from the second tube, such that the lift gage measures a gap between the second tube and the armature. The present invention also provides a method of setting armature/needle lift in a fuel injector having an external inlet tube, an internal inlet tube having an upstream end and a downstream end, an armature/needle assembly including an armature having an upstream end and a needle having an upstream end connected to the armature, and a seat, the method comprising: inserting a lift pin into the upstream end of the internal inlet tube; inserting a lift check gage through the lift pin into the internal inlet tube such that a downstream end of the lift check gage engages the upstream end of the needle and such that the armature/needle assembly is biased downstream, the needle engaging the valve seat; fixedly positioning an upstream end of the lift check gage; moving the internal inlet tube downstream such that the downstream end of the internal inlet tube engages the armature; moving the lift pin and the internal inlet tube upstream a predetermined distance as measured by the lift check gage; removing the lift check gage and the lift pin from the internal inlet tube; and securing the internal inlet tube to the external inlet tube.